Refrigeration



Dec. 23, 1941.

A. LENNING REFRIGERATION Filed Feb. 23, 1938 4 Sheets-Sheet '1 AL}, ATTORNEY.

Dec. 23, 1941. A. LENNING 2,267,283

REFRIGERATION Filed Feb. 23, 1958 4 Sheets-Sheet 2 -INVENTO R.

QM MMM lug ATTORNEY.

A. LENNING Dec. 23, 1941.

REFRIGERATION Filed Feb. 23, 1938 4 Sheets-Sheet I5 7 INVENTOR.

Mm ATTORNEY.

Dec. 23, 1941. A. LENNING REFRIGERATION Filed Feb. 2a, 1938 4 Sheets-Sheet 4 INVENTOR- BY (lb/11 A4,, ATTORNEY.

Patented Dec. 23, 1941 2,267,283 REFRIGERATION Alvar Lenning, Stockholm, Sweden, assignor, by mesne assignments, to Serve], Inc., New York, N. Y., a corporation of Delaware Application February 23, 1938, Serial No. 191,856 In Germany February 24, 1937 2 14 Claims.

flowing to such place of evaporation before the inert gas is conducted to another place of evaporation. With this arrangement, the mean temperature of one place of evaporation is lowered and the mean temperature differential between such place of evaporation and another place of evaporation is increased.

The invention, together with the above and other objects and advantages thereof, will be more fully understood upon reference to the following description and accompanying drawings forming a part of this specification and of which Fig. 1 illustrates more or less diagrammatically a refrigeration system embodying the invention;

Fig. 2 is a view diagrammatically illustrating another manner of carrying out the invention shown in Fig. 1;

Fig. 3 is a fragmentary rear elevationof a refrigerator cabinet in which parts of the refrigeration system shown in Fig. 2 are mounted;

Fig. 4 is a vertical sectional view of the refrigerator'shown in 'Fig. 3 and taken at lines 4-4 of. Figs. 5 and 6;

Fig. 5 is a vertical sectional view taken at line 5-5 of Fig. 4; and

Fig. 6 is a horizontal sectional view taken at line 66 of Fig. 5.

Referring to Fig. 1, the invention is embodied in a refrigeration system of a uniform pressure type, generally as described in Patent No. 1,837,767 to Thore M. Elfving, in which an auxiliary pressure equalizing gas is employed. In a system of this type ,a refrigerantfluid, such as liquid ammonia, for example, may be introduced through conduits l0 and l l into a cooling unit 12 which is arranged in a thermally insulated storage space l3. The refrigerant fluid evaporates and diffuses in cooling unit l2 into an inert gas, such as hydrogen, for example, to produce a refrigerating effect. The resulting rich gas mixture of refrigerant and inert gas fiows from cooling unit I 2 through an outer passage M of gas heat exchanger l5 and vertical conduit l6 into the lower end of an absorber IT. The absorber I1 is diagrammatically shown in the form of a looped coil provided with a plurality of cooling fins l8.

In absorber l1 refrigerant vapor is absorbed by a suitable absorbent, such as water, which enters through a conduit l9. The hydrogen or inert gas, which is practically insoluble and weak in refrigerant, is returned to the upper part of cooling unit 12 through an inner passage 20 of the gas heat exchanger and conduit 2|; and the enriched absorption liquid flows into an accumulation vessel 22. From vessel 22 enriched liquid flows through a conduit 23, an outer passage of liquid heat exchanger 24, and conduit 25 into rear chamber 26 of a generator 21;

By heating generator 21, as by a gas burner 28, for example, liquid is raised by'vapor-lift action from chamber 26 through conduit 29 into- The liberchamber 3|, flows upward through an air-cooled rectifier 32 into an air-cooled condenser 33 pro-- vided with a plurality of cooling fins 34. Refrigerant vapor is liquefied in condenser 33 and returned to cooling unit 12 through conduits II and I2, as will be described hereinafter, to complete the refrigerating cycle.

The weakened absorption liquid from which refrigerant vapor has been expelled is conducted from chamber 3| through conduit 35, an inner passage of liquid heat exchanger 24 and conduit l9 into the upper part of absorber H.

The cooling unit l2 comprises two cooling elements I21: and l2b. Refrigerant vapor from generator 21 flows upward through rectifier 32 into condenser section 33a of the air-cooled condenser 33. Refrigerant liquefied in condenser section 33a flows into a U-shaped conduit 36 and thence through a conduit 31 into a liquid pre- The precooled liquid flows from precooler 38 through conduit In into the upper part of cooling element l2a.

Refrigerant vapor not liquefied in condenser section 33a flows from the right-hand leg of conduit 36 into a second condenser section 33b. Refrigerant liquefied in condenser section 33b also flows into conduit 35 and thence through conduit 31, precooler 38, and conduit Ill .into cooling element l2a. Refrigerant not liquefied in condenser section 33b flows from the lefthand leg of conduit 36 into a third condenser section 33c. Refrigerant liquefied in condenser section 330 fiows into the lower end of a vertical conduit 4| and thence through conduit ll into the upper part of cooling element l2b. The conduits III, II, and 31 are formed to provide liquid traps whereby the condenser is sealed from cooling element l2b and precooler 38 and the latter is sealed from cooling element He.

The lower end of condenser section 330 is connected by conduit 4i, vessel 42, and conduit 43 to the gas circuit, as at the gas heat exchanger l5, for example, so that any inert gas which may pass into the condenser can flow into the gas circuit. Refrigerant vapor not liquefied in the condenser fiows through-conduit 4| to displace inert gas in vessel 42 and force such inert gas through conduit 43 into the gas circuit. By forcing gas into the gas circuit in this manner, the total pressure in the system is raised whereby an adequate condensing pressure is obtained to insure condensation of refrigerant vapor in the condenser.

The cooling element I20, is shown in the form of a coil. This coil may be embedded in or otherwise suitably arranged in heat exchange relation with a shell, as shown in Figs. 4 and 5, to provide a plurality of freezing compartments adapted to receive trays for freezing water and other matter to be frozen. The cooling element I2!) is arranged with a plurality of cooling heat transfer fins 44 whereby a relatively extensive surface is provided for cooling air in storage space l3.

The cooling elements Ho and l2b are connected in series relation with inert gas flowing downwardly therethrough in the presence of and in parallel fiow with liquid which is introduced through conduits I0 and II. The gas in the upper cooling element He, therefore, contains a lesser amount of refrigerant vapor than the gas in the lower cooling element I211. The partial vapor pressure of refrigerant in the gas mixture formed in the cooling elements is a gradient, so that the evaporating temperature of liquid refrigerant in the cooling elements is also a gradient, the evaporating temperature of liquid being lower in the upper cooling element In which constitutes the freezing portion of the cooling unit.

In accordance with this invention, an auxiliary gas heat exchanger 45 is provided in the gas circuit whereby gas flowing from cooling element l2a flows in heat exchange relation with gas flowing toward cooling element i2a before such gas enters cooling element l2b. With this arrangement, heat is transferred from weak gas entering cooling element In to cool gas leaving the cooling element, thereby lowering the temperature of the gas entering the cooling element I211. By cooling the weak gas in this manner before it enters the cooling element I211 the mean temperature of the upper cooling element is lowered, thereby improving the operation of this portion of the cooling unit and always insuring a sufficiently low temperature for freezing water and the like.

Due to gas heat exchanger 45, gas enters the lower cooling element i2b at a higher temperature than it would if enteringdirectly from the upper cooling element I 2a. With this arrangement, therefore, the mean temperature of the lower cooling element is increased. Thus, by lowering the mean temperature of the freezing portion of the cooling element and raising the mean temperature of the space cooling portion thereof, a wide temperature differential of the mean temperatures of the two portions is effected. I

The condenser sections 33a, 33b, and 330 may be arranged and dimensioned in such a manner that liquid refrigerant is supplied to cooling element l2b through conduit II when the cooling air reaches a predetermined high temperature. If desired, a conduit forming a liquid seal or trap may be provided which connects the lower part of cooling element I241 and upper part of cooling element l2b, so that unevaporated liquid flows directly from the upper to the lower cooling element. Such a conduit connection 46 is indicated in dotted lines in Fig. 1. Instead of providing the conduit connection 46, unevaporated liquid may be permitted to flow from cooling element lZa into the auxiliary gas heat exchanger and thence into the lower cooling element i222. In such case evaporation of liquid takes place in gas heat exchanger 45, thereby exercising considerable influence in cooling weak gas flowing toward cooling element l2a.

The auxiliary gas heat exchanger 45 is at a higher temperature than cooling element I21: and at a lower temperature than gas heat exchanger l5. In order to prevent loss of cold the auxiliary gas heat exchanger may be insulated in any suitable manner. As shown in Fig. 1, the auxiliary gas heat exchanger 45 and precooler 38 are both embedded in insulation in a removable wall part 41 of the cabinet forming the thermally insulated storage sapce IS. The gas heat exchanger I5 is also embedded in insulation, particularly the upper cold portion thereof, to prevent loss of cold.

If desired, the auxiliary gas heat exchanger may be arranged in storage space l3 and employed as an additional space cooling element.

Such a modification is shown in the system diagrammatically illustrated in Fig. 2. The parts of the system shown in Fig. 2 which are similar to parts in Fig. 1 are designated by the same reference numerals. In Fig. 2, the generator 21a is of a vertical type having a vapor-lift coil 48 disposed about the lower end of a flue 49 which extends through the generator. Enriched absorption liquid flowing from vessel 22 is raised by vapor-lift action from coil 48 through conduit 50 into the upper part of the generator. The weakened absorption liquid flows from the lower part of the generator through conduit 35, liquid heat exchanger 24, and vertical conduit 19 into the upper part of absorber ll.

In the system in Fig. 2 the air-cooled rectifier 32a is located above condenser section 33a. The condenser sections 33a, 33b, and 33c otherwise are arranged in a manner similar to that shown in Fig. 1. The conduit II in Fig. 2 is arranged in heat exchange relation with the outer passage of the horizontal gas heat exchanger I51: and

through which passes the rich gas leaving cooling element I 2b. The conduit II is connected to deliver liquid refrigerant to the upper part of auxiliary gas heat exchanger 45awhich is located within storage space I3.

In this modification weak gas from absorber I'I flows through conduit 5|, the outer passage of gas heat exchanger 15a, conduit 52, .the inner partment 59.

passage of auxiliary gas heat exchanger 45a, and conduit 2| into the upper part of cooling element [2a. The gas flows downwardly through cooling element In, the outer passage of auxiliary gas heat exchanger 45a, and cooling element l2b in parallel flow with liquid which enters through conduits l and II. From cooling partment 59; The compartment 59 forms a flue through which air flows upwardly by natural draft over the surfaces of the condenser and absorber and cooling fins fixed thereto.

element I2b rich gas flows through the inner passage of gas heat exchanger 15a and conduit IE to the lower part of absorber II. The coldest part of gas heat exchanger la is also arranged within storage space l3 inasmuch as it may also be efiectively employed for space cooling.

The particular arrangement of the condenser sections 33a, 33b, and 33c is particularly favorable for quickly producing below freezing temperatures in cooling element l2a when operation of the system is started after a shutdown or idle period. The refrigerant first liquefied in condenser section 33a flows into precooler 38 where it is precooled independently of the temperature of the space cooling element l2b. By precooling the liquid and lowering the temperature of the inert gas by the provision of the auxiliary gas heat exchanger, therefore, freezing temperatures are quickly produced by the upper cooling element l2a. By locating the auxiliary gas heat exchanger 45a in storage space I 3 the heat transfer surface provided for cooling air is increased considerably. The surfaces of the auxiliary gas heat exchanger 45a as well as cooling element l2b may be maintained above the freezing temperature so that air in the storage space is kept at a relatively high humidity. This relatively high humidity is effected under these conditions because less water vapor is removed from. air flowing in contact with the surfaces of the auxiliary gas heat exchanger 45a and lower cooling element l2b when these elements are maintained above rather than below the freezing temperature. Y

In Figs. 3 to 6 inclusive a practical embodiment of the invention is diagrammatically shown wherein the system in Fig. 2 is incorporated in a household refrigerator. The refrigerator cludes a cabinet 54 having an inner metal shell 55 arranged to be supported within an outer metal shell 56 and insulated therefrom with any suitable insulating material 51. The inner metal shell 55 defines the storage space l3 into which access is afforded by a door 58 hinged to the front of the cabinet.

The rear wall of storage space I3 is provided with an opening into which fits the removable wall part 41, as shown most clearly in Figs. 4 and 6. The opening is substantially the width of storage space l3 so that cooling element I24: and 12b can readily be positioned in space l3 when the cover 41 is fitted into the opening. The gas heat exchanger |5a extends through the removable wall part 41 as also do th conduits connecting the cooling elements l2a and I2!) and the condenser 33.

The lateral side walls of the outer shell 56 extend beyond the rear insulated wall of storage space I3 to provide a vertically extending compartment 59 in which parts of the system may be located. In Fig. 3 the condenser 33 and vessel 42 are arranged in the upper part of the com- The positions of the remaining parts of the system have not been shown in the drawings since their illustration is not necessary for an understanding of the invention. The remaining parts, however, may be positioned in any suitable manner in the lower part of com- The upper cooling element l2a is formed as a looped coil having top and bottom parts shaped as shown in Fig. 6. This coil is arranged in heat exchange relation with a shell 60 which extends across the storage space l3 and is provided with a plurality of compartments 6| adapted to receive ice trays G2 and the like. The entire 0001- ing unit may be provided with a front baffle plate (not shown) having suitable openings to permit insertion and removal of trays into and from the compartments iii. A suitable door (not shown) is preferably provided to close the freezing compartment 6|.

The upper cooling element 12a is provided with a suitable insulating covering 63 which may be formed of semi-vulcanized porous rubber, such as, for example, sponge rubber or the like. The

covering 63 may be provided with a plurality of short fins 64. Due to the insulating cover 63 and heat absorbing effect of the fins 64, the surfaces of the freezing portion of the cooling unit may be maintained at or above the freezing temperature. By providing the fins 64 the insulating covering 63 may be made of less thickness than would otherwise be possible, because heat from air in the storage space is transferred to these fins and distributed over the smooth outer surface of the covering 63 which may be made less, porous than the other parts of the covering. With this construction the likelihood of frost forming on the upper freezing portion of cooling unit I2 is avoided.

In order that the temperature of cooling element l2a will be mainained as low as possible at all times it is arranged at the top of storage space l3 in such a manner that the greater portion thereof is withdrawn from contact with air circulating in the space, thereby reducing the likelihood of frost forming on the surfaces thereof. While cooling element I2ais protected as much as possible from air circulating in space l3, the lower cooling element I2?) is arranged so that the surfaces thereof will effectively contact in Fig. 6. In order to improve the natural circulation of air which is induced by air coming in contact with the lower coil and fins 44, a baffle plate 65 is positioned beneath the lower coil. The battle plate 65 screens off the lower parts of fins 44 and the lower coil so that air cooled by flowing in contact with these surfaces does not immediately flow downward therefrom. The baffle plate 65 is provided with a central opening 66 so that natural circulation of air takes place substantially in the manner indicated by the arrows in Fig. 5.

The inner and outer edges of baffle plate 55 are provided with flanges 61 to form a trough for collecting water that may drip from the lower cooling element l2b. The trough formed by baflle plate 65 is provided with a rear opening 68' vals or a drain conduit may be provided whereby the water automatically flows to a place outside the storage space l3.

While several embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the spirit and scope of the invention, as pointed out in the following claims.

What is claimed is:

1. In an absorption refrigeration system having a plurality of evaporators at different levels and through which inert gas flows downward in series, means for supplying liquid refrigerant to said evaporators, a first heat exchanger between gas flowing to an upper evaporator and gas flowing from said upper evaporator to a lower evaporator, a second heat exchanger for gas flowing from said lower evaporator and gas flowing to said upper evaporator, and means to thermally insulate said first gas heat exchanger.

2. In combination with a refrigerator having a thermally insulated storage compartment and an absorption refrigeration system having a plurality of evaporators at different levels and through which inert gas flows downward in series, and means for supplying liquid refrigerant a thermally insulated storage compartment and.

an absorption refrigeration system having a plurality of evaporators at different levels and through which inert gas flows downward in series, and means for supplying liquid refrigerant to said evaporators, a heat exchanger between gas flowing to an upper evaporator and gas flowing from said upper evaporator to a lower evaporator, and said upper evaporator being so constructed and arranged that it'extends substantially from one side wall to the opposite side wall of said compartment just beneath the top wall of said compartment and is provided with a plurality of freezing chambers located alongside of each other.

4. In combination with a refrigerator having a thermally insulated storage compartment and an absorption refrigeration system having a plurality of evaporators at different levels and through which inert gas flows downward in series, and means for supplying liquid refrigerant to said evaporators, a heat exchanger between gas flowing to an upper evaporator and gas flow-' ing from said upper evaporatorto a lower evaporator, said upper evaporator being thermally segregated from said storage compartment and arranged in the upper part thereof and having an opening to permit the insertion and with drawal of one ormore ice trays, and both said heat exchanger and lower evaporator being arranged for, cooling air in said compartment.

5. In combination with a refrigerator having a thermally insulated storage compartment and ing from said upper evaporator to a lower evaporator, said upper evaporator being thermally segregated from said storage compartment and located in the upper part thereof and having an opening to permit the insertion and withdrawal of one or more ice trays, and said lower evaporator being in the form of a finned pipe coil for cooling air in said compartment.

6. In a refrigerator having a storage compartment and an absorption refrigeration system having a low temperature evaporator and a higher temperature evaporator to both of which liquid refrigerant is supplied for evaporation in the presence of an inert gas, a first pipe for conducting gas to said low temperature evaporator, and a second pipe for conducting all of the gas from said low temperature evaporator to said higher temperature evaporator, said first pipe being out of heat exchange relation with a major portion of said higher temperature evaporator and in heat exchange relation with said second pipe to exchange heat from gas flowing in said first pipe to said low temperature evaporator to gas flowing in said. second pipe from said low temperature evaporator to said higher temperature evaporator, whereby the mean temperature of said low temperature evaporator is lowered and the mean temperature of said higher temperature evaporator'is raised, and said low temperature evaporator being arranged to serve as a freezer and said higher temperature evaporator being arranged to cool air in said compartment.

7. In the art of refrigeration with the aid of a refrigeration system having first and second places of evaporation to which liquid refrigerant is supplied for evaporation therein in the presence of an inert gas, flowing inert gas to said first place of evaporation in a first path of fiow out of heat exchange relation with a major portion of said second place of evaporation, flowing all of the inert gas in a second path of fiow from said first place of evaporation to said second place of evaporation, and evaporating liquid in said second place of evaporation by heat abstracted from its surroundings, lowering the mean temperature of said first place of evaporation by abstracting heat from gas in said first path of flow and flowing to said first place of evaporation, and raising the mean temperature of said second place of evaporation by heating gas in said second path of flow and flowing from said first place of evaporation to said second place of evaporation.

8. In the art of refrigeration with the aid of a refrigeration system having two places of evaporation to which liquid refrigerant is supplied for evaporation therein in the presence of an inert gas, flowing inert gas to said first place of evaporation in a first path of flow out of heat exchange relation with a major portion of said second place of evaporation, flowing all of the gas in a second path of flow from said first place of evaporation to said second place of evaporation, and evaporating liquid refrigerant in said second place of evaporation by heat abstracted from its surroundings, lowering the mean temperature of said first place of evaporation by abstracting heat from gas in said first path of flow and flowing tosaid first place of evaporation, and raising the mean temperature of said-second place of evaporation by utilizing said abstracted heat'to heat gas in said second path of flow and flowing from said first place of evaporation to said second place of evaporation.

9. In a refrigerator having a storage compartment and an absorption refrigeration system having first and second evaporators through which inert gas flows downward in series and to which liquid refrigerant is supplied for evaporation therein in the presence of said gas, a first pipe for conducting gas to said first evaporator, a second pipe for conducting gas from said-first evaporator to said second evaporator, said first pipe being out of heat exchange relation with a major portion of said second evaporator and in heat exchange relation with said second pipe to exchange heat from gas flowing in said first pipe to gas flowing in said second pipe from said first evaporator to said second evaporator, whereby the mean temperature of said first-evaporator is lowered and the mean temperature of said second evaporator is raised, and said second evaporator being arranged to cool air in said compartment. I

10. .In the art of refrigeration with the aid of an absorption refrigeration system having first and second evaporators to which liquid refrigerant' is supplied for evaporation in the presence of an inert gas, flowing inert gas in a first path of flow out of heat exchange relation with a major portion of said second evaporator, flowing gas from said first path of flow to an upper part of said first evaporator for downward flow therein, flowing gas in a second path of flow from the lower part of said first evaporator to the upper part of I said second evaporator for downward flow in the latter, and exchanging heat from gas in said first path of flow and flowing to said first evaporator to gas in said second path of flow and flowing from said first evaporator to said second evaporator.

11. In a refrigerator having a storage compartment and an absorption refrigeration system having a gas circuit including an absorber and first and second evaporators to which liquid refrigerant is conducted for evaporation therein in the presence of an inert gas, a first pipe for conducting inert gas from said absorber to said first evaporator, a second pipe for conducting gas from said first evaporator to said second evaporator, and a third pipe for conducting as from said second evaporator to said absorber,said third pipe being in heat exchange relation with said first pipe through which gas flows to said first evaporator, said first pipe being out of heat exchange relation with a major portion of said second evaporator, said second pipe being in heat exchange relation with said first pipe at a region through which inert gas flows to said first evapo-' 12. In combination with a refrigerator having a thermally insulated storage compartment and an absorption refrigeration system having upper and lower evaporators to which liquid refrigerant is supplied for evaporation in the presence of an inert gas, a heat exchanger between gas flowing to said upper evaporator and gas flowing from said upper evaporator to said lower evaporator, said upper evaporator being thermally segregated from said compartment and located in the upper part thereof and having an opening to permit-the insertion and withdrawal of one or more ice trays, said lower evaporator including a pipe coil having a relatively extensive heat transfer surface for cooling air in said compartment, and a baflie plate in said compartment below said lower evaporator, said plate having a central opening and being of such shape and size that circulation of air takes place upwardly adjacent the side walls of said compartment and downward1y through said opening.

13. In a refrigerator as set forth in claim 12, a

trough associated with said baflle plate for '00]- lecting water dripping from said lower evaporator.

14. A refrigerator comprising -a ,cabinet having a storage compartment, the storage compartment being open at the front of the cabinet, absorptionrefrigeration apparatus containing inert gas in the presence of which liquid refrigerant evaporates, said apparatus including low temperature and high temperature evaporators, said high temperature evaporator being arranged to abstract heat from the storage compartment and said low temperature evaporator being disposed at a higher level than said high temperature evaporator and located in the upper part of the evaporator, and a door for the cabinet opening for inserting and removing food products and the like into and from the storage compartment and also affording access to the freezing receptacle formed by said low temperature evaporator.

ALVAR LENNING. 

